A process for protecting a substrate from heat and fire

ABSTRACT

The invention relates to a process for protecting substrates with intumescent compositions comprising certain arylsulfonylureas, such as p-amino-benzenesulfonylurea, paminobenzenesulfonylthiourea, etc. The intumescent agents may be employed in conjunction with additives conventionally used in intumescent compositions.

States Patent Oct. 30, 1973 i 1 PROCESS FOR PROTECTING A SUBSTRATE FROM HEAT AND FIRE Shirley ll. Roth, Highland Park, NJ.

Cities Service Company, New York, N.Y.

Jan. 21, 1972 Inventor:

Assignee:

Filed:

Appl. No.:

U.S. Cl. 117/136, 106/15 FP, 117/147, 252/8.1

Int. Cl C0911 5/18 Field of Search 260/397.7, 552 R, 260/553 D; 117/136; 252/81; 106/15 PP References Cited UNITED STATES PATENTS 9/1945 l-laack 260l397.7 D

2,498,782 2/1950 Arquet et al 260/552 R Primary Examiner-William D. Martin Assistant Examiner-Theodore G. Davis [5 7 ABSTRACT 5 Claims, No Drawings PROCESS FOR PROTECTING A SUBSTRATE FROM HEAT AND FIRE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to intumescent compositions and more particularly relates to such compositions containing a one-component intumescent agent.

2. Description of the Prior Art It is known that a substrate may be protected from heat and fire by the application of an intumescent composition. lntumescent compositions of the prior art usually contain an intumescent agent having at least three components; i.e., a carbonific, a spumific, and a catalyst; and they are typically characterized by the disadvantages of high cost, low spreading rate, relatively poor efficiency, poor water resistance, and poor weatherability.

As disclosed in U. S. Pat. No. 3,535,130, it has already been discovered that a one-component intumescent agent has advantages over multicomponent intumescent agents. However, the intumescent agents of the patent have poor adherence to substrates and have an undesirable degree of moisture sensitivity.

SUMMARY OF THE INVENTION wherein Ar is a divalent aromatic residue, R- is hydrogen or a hydrocarbon, halohydrocarbon, or acyl radical, and X is oxygen or sulfur.

DESCRIPTION OF THE PREFERED EMBODIMENTS The intumescent agents of the invention may be any compounds corresponding to the above formula. However, they are preferably compounds wherein Ar is a divalent aromatic residue derived from benzene or napthalene or an alkyl, haloalkyl, alkoxy, haloalkoxy, halo, hydroxy, carboxy, amino, amido, or nitro derivative thereof. When the aromatic ring bears organic substituents, it is usually preferred that these substituents contain 1-5 carbon atoms. When there are halo substituents, it is usually preferred that they be chloro or bromo. It is also preferred that the aromatic ring have at least one free reactive position.

As indicated above, R of the formula may be hydrogen or a hydrocarbon, halohydrocarbon, or acyl radical, e.g., an alkyl, chloroalkyl, or bromoalkyl radical containing one to five carbon atoms, a phenyl, chlorophenyl, or bromophenyl radical, or an aliphatic or aromatic acyl radical.

Exemplary of the intumescent agents of the invention are p-aminobenzenesulfonylurea, 4-amino-3- chlorobenzenesulfonylurea, 2-amino-4- bromobenzenesulfonylurea, 4-amino-2- ethylbenzenesuflonylurea, 3-amino-4-chloromethylbenzenesulfonylurea, 4-amino-2- butoxybenzenesulfonylurea, 4-amino-3- chloromethoxybenzene-sulfonylurea, 4-amino-3-carboxybenzenesulfonylurea, 3,4- diaminobenzenesulfonylurea, 4-amino-2-acetamidobenzene-sulfonylurea, 2-amino-4- nitrobenzenesulfonylurea, 4- methylaminobenzenesulfonylurea, 4-chloroethylamino-benzenesulfonylurea, 4- bromomethylaminobenzenesulfonylurea, 4- phenylaminobenzenesulfonylurea, 4-( p-chlorophenylamino)benzenesulfonylurea, 4-(p-bromophenylamino)-benzenesulfonylurea, pacetamidobenzenesulfonylurea, pbenzamidobenzenesulfonylurea, the corresponding naphthalene compounds, and the corresponding thio urea compounds. Preferred intumescent agents include p-amino-benzenesulfonylurea and p-aminobenzenesulfonylthiourea. When not readily available, these compounds may be prepared by known techniques.

For use in protecting a substrate from heat and fire, the intumescent agents of the invention may be applied in any suitable manner, e.g., electrodeposition, spraying of powdered intumescent agent onto an adhesive substrate, etc. However, it is usually preferred to compound the intumescent agent with a binder, e.g., nitrocellulose, and optionally also with one or more of the other ingredients conventionally used in intumescent compositions, e.g., stabilizers, dispersing agents, pigments, driers, biocides, anti-foamers, thickeners, protective colloids, fillers, blowing agents, etc.; disperse the composition in a suitable liquid medium, e.g., water or a solvent or solvent mixture; and apply the coating composition thus formed to the substrate to be protected. As is the case with conventional intumescent coating compositions, it is frequently convenient to apply these coating compositions in the form of a paint having a solids content of about 10-70 percent by weight and an intumescent agent/binder weight ratio of about 0.075-l4/l to deposit a coating having a dry thickness of about 0.00l-0.75 inch.

The intumescent agents of the invention are efficient, have low moisture sensitivity, and intumesce to form foams having good volume, cell structure, and adherence to substrates, such as wood, metal, and plastics. They are also useful as flame retardants in normally flammable compositions.

The following example is given to illustrate the invention and is not intended as a limitation thereof.

EXAMPLE I Place one gram of p-aminobenzenesulfonylurea in an aluminum pan and flame it with a propane torch. The compound intumesces to form an excellent volume of foam having a good cell structure.

Similar results are also observed when p-aminobenzenesulfonylthiourea and the other intumescent agents mentioned in the specification are substituted for the intumescent agents of the Example.

It is obvious that many variations may be made in the products and processes set forth above without departing from the spirit and scope of this invention.

What is claimed is: l. A process for protecting a substrate from heat and fire which comprises applying thereto an intumescent composition comprising as the intumescent agent a compound corresponding to the formula:

OHX

wherein Ar is a divalent aromatic residue, R is hydrogen or a hydrocarbon, halohydrocarbon, or acyl radical, and X is oxygen or sulfur.

agent is p-aminobenzenesulfonylthiourea.

gwq UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 769 ,079 Dated October 30 I 1973 Inv n flfi) Shirley H. Roth It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

- 1 Column 1, lines 35-46, the portion of the formula reading II X ll X 9 shouldread u c C Signed and sealed this 2nd day of April 197A.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. C. MARSHALL DANN Attesting Officer I Commissioner of Patents mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIDN Patent No. 3,769,079 Dated October 30, 1973 Inventor( Shirley H. Roth It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

A '1 Column 1, lines 35-46, the portion of the formula reading II X II X 9 should read u C C Signed and sealed this 2nd day of April 197A.

(SEAL) Attest:

EDWARD PLFLETCHERJR. C. MARSHALL DANN Atte sting Officer Commissioner of Patents 

2. The process of claim 1 wherein Ar is a divalent aromatic residue derived from benzene or naphthalene or an alkyl, haloalkyl, alkoxy, haloalkoxy, halo, hydroxy, carboxy, amino, amido, or nitro derivative thereof.
 3. The process of claim 2 wherein Ar is a divalent aromatic residue derived from benzene.
 4. The process of claim 3 wherein the intumescent agent is p-aminobenzenesulfonylurea.
 5. The process of claim 3 wherein the intumescent agent is p-aminobenzenesulfonylthiourea. 